Change password of password keys

[stemid]

Only administrators should be able to connect password keys.

Modified to instead focus on changing passwords on password keys.

[stemid]

Might be able to solve this by changing passwords for password keys. Will investigate.

[stemid]

Looks like this is half completed in the siptracklib method PasswordKey.changeKey, in twisteds PasswordKeyRPC.xmlrpc_change_key and in siptrackdlib.PasswordKey.changePassword.

So I've sent a question to @sii about this.